1. Field
The present disclosure relates generally to aircraft and icing conditions and, in particular, to simulating icing conditions for aircraft. Still more particularly, the present disclosure relates to a method and apparatus for simulating operation of an inlet ice protection system in an icing condition.
2. Background
In aviation, icing on an aircraft may occur when the atmospheric conditions lead to the formation of ice on the surfaces of the aircraft. Further, this ice also may occur within the engine. Ice formation on the surfaces of the aircraft, on inlets of an engine, and other locations is undesirable and potentially unsafe for operating the aircraft.
Icing conditions may occur when drops of supercooled liquid water are present. Water is considered to be supercooled when the water is cooled below the stated freezing point for water but is still in liquid form. Icing conditions may be characterized by the size of the drops, the liquid water content, the air temperature, and/or other parameters. These parameters may affect the rate and extent at which ice forms on an aircraft.
Drops of water may be supercooled in various environments. For example, drops of water may be supercooled in stratiform clouds and in cumulous clouds.
When icing occurs, the aircraft may not operate as desired. For example, ice on the wing of an aircraft may cause the aircraft to stall at a lower angle of attack. Further, icing on the wing may case the aircraft to and have an increased drag.
Aircraft may have mechanisms to prevent icing, remove ice, or some combination thereof to handle these icing conditions. For example, aircraft may include ice protection systems that detect icing on the aircraft, prevent ice from forming on the surface of the aircraft, remove ice from the surface of the aircraft, or some combination thereof. Ice may be prevented from forming on the surface of the aircraft using bleed air, infrared heating, and other suitable mechanisms.
Different government regulations may define types of icing conditions that are to be considered during the design of an aircraft and the certification of the aircraft. The regulations may require the use of icing protection systems to protect different surfaces, such as surfaces on the wing, fuselage, and engine, from icing conditions as part of a certification process for an aircraft.
Analysis and testing of aircraft designs is often conducted using simulations of icing conditions performed in wind tunnels. These wind tunnels are configured to imitate environments in which the aircraft operate where icing conditions may be present. These types of wind tunnels may be referred to as icing wind tunnels.
Testing icing protection systems with aircraft structures may be more difficult than desired due to the size, complexity, and other factors that may be present with particular types of aircraft structures.
For example, some aircraft structures may be larger than desired for testing in an icing wind tunnel. In other words, the size of an icing wind tunnel may limit what structures may be tested in the icing wind tunnel.
Additionally, some icing protection systems may be complex. The complexity of the icing protection system may make testing the icing protection system in an icing wind tunnel more difficult than desired. For example, the icing protection system for an aircraft may involve numerous control systems, wires, power sources, and other components. Connecting these different components to structures of an aircraft in an icing wind tunnel may be more difficult for testing than desired. As a result, testing icing protection systems may be more difficult than desired.
Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.